Each person on a team brings a unique perspective to the process; i.e., how things work; what happens when changes are made, and how to sustain improvements during daily work. Contributions are made from each individual's skill set and the team's synthesis of ideas.
Division of labor is the economic term for the practice of assigning small parts of a complicated job to individual workers who specialize in doing just their small part.
In the short term, the labor market (and other things) aren't in equilibrium. For example, there may be a shortage of workers in an industry, or prices have not fully adjusted yet. In the long term, equilibrium is assumed. In the short run, economists talk about things like short run macro policy (fiscal/monetary policy like raising taxes/lowering spending, raising interest rates, etc). In the long run, economists talk about structural issues, savings/investment and consequently growth.